Am I getting scammed

So I’ve been on gameflip for a while, mostly to sell steam wallet codes so that I would be able to add the proceeds from the purchases to my paypal balance. So far I’ve sold a couple cards with no issue, but today somebody made a dispute saying that when they tried to use the code, it was already used. I took a look and noticed that the person making the dispute was relatively new to gameflip, with their account being created this March. Nobody else I sold to had issues with their purchases and the deals went through smoothly, except for this one case. Is this a scam and have there been any other scam attempts similar what’s happening right now?
Invite Code: 9SQKYC

Hello! I just checkd your sale and saw that we sent the buyer a ticket asking for more information about this issue. Please send me a PM with the activation time for this code in particular (in order to get that, please contact Steam support). I’ll be able to help you further.

Thanks!

Hello, thanks for responding. Just a quick question, how do I get the activation time? I’m not sure how to contact steam support about it.

Please check this link for further help about your question:

https://support.steampowered.com/kb_article.php?ref=1223-qroc-4460


This is what shows up when I try to ask steam support about anything. The first choice would indicate that my steam code was damaged, but that’s not necessarily the case since I just want to find the activation time. Do I still use that link and ask for the activation time instead?
This is the link I’m talking about https://help.steampowered.com/en/wizard/HelpWithDamagedWalletCode

I think you can contact them that way, but I can’t confirm. Please try and let me know. Also let’s continue this conversation via PM.

Thanks!